CA2928241C

CA2928241C - Protective helmets with non-linearly deforming elements

Info

Publication number: CA2928241C
Application number: CA2928241A
Authority: CA
Inventors: Samuel R. Browd; Jonathan Posner; Per G. Reinhall; David L. Marver; John T. Ii Dardis
Original assignee: University of Washington Center for Commercialization
Current assignee: University of Washington Center for Commercialization
Priority date: 2013-11-05
Filing date: 2014-11-05
Publication date: 2020-06-30
Anticipated expiration: 2034-11-05
Also published as: JP2016535823A; US20210186139A1; CN106413430A; EP3065577A2; CA2928241A1; US10966479B2; WO2015069800A2; EP3065577A4; WO2015069800A3; US20160255900A1

Abstract

The present technology relates generally to protective helmets with non-linearly deforming members. Helmets configured in accordance with embodiments of the present technology can comprise, for example, an inner layer, an outer layer, a space between the inner layer and the outer layer, and an interface layer disposed in the space. The interface layer comprises a plurality of filaments, each having a height, a longitudinal axis along the height, a first end proximal to the inner layer, and a second end proximal to the outer layer. The filaments are sized and shaped to span the space between the inner layer and the outer layer. The filaments are configured to deform non-linearly in response to an external incident force on the helmet.

Description

PROTECTIVE HELMETS WITH NON-LINEARLY
DEFORMING ELEMENTS
TECHNICAL FIELD
[0001] The present technology is generally related to protective helmets.
In particular, several embodiments are directed to protective helmets with non-linearly deforming elements therein.
BACKGROUND

[0002] Sports-related traumatic brain injury, and specifically concussion, have become major concerns for the NFL, the NCAA, football teams and participants at all levels. Such injuries are also significant concerns for participants in other activities such as cycling and skiing. Current helmet technology is inadequate, as it primarily protects against superficial head injury and not concussions that can be caused by direct or oblique forces. Additionally, currently available helmets absorb incident forces linearly, which transmits the bulk of the incident force to the head of the wearer.
SUMMARY

[0003] Accordingly, in one aspect there is provided a helmet comprising: an inner layer;
an outer layer spaced apart from the inner layer to define a space; and an interface layer disposed in the space between the inner layer and the outer layer, the interface layer comprising a first plurality of filaments and a second plurality of filaments, each of the first and second plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer, each of the first and second plurality of filaments having a longitudinal axis and having an average aspect ratio of between 3:1 and 1,000:1, wherein an external incident force creates a local deformation region of the helmet, wherein the first plurality of filaments within the local deformation region is configured to buckle in response to the external incident force, and wherein the second plurality of filaments immediately adjacent to the local deformation region does not buckle in response to the external incident force on the helmet.
- -

[0004] According to another aspect there is provided a helmet comprising:
an inner layer; an outer layer spaced apart from the inner layer to define a space; and an interface layer disposed in the space between the inner layer and the outer layer, wherein the interface layer comprises: a first plurality of filaments, each of the first plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer; a second plurality of filaments, each of the second plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer; and each of the first and second plurality of filaments having a longitudinal axis and having an average filament aspect ratio of between 3:1 and 1,000:1, wherein an external incident force creates a local deformation region of the helmet, at least a first portion of the first plurality of filaments within the local deformation region is configured to buckle in response to the external incident force and a second portion of the first plurality of filaments immediately adjacent to the local deformation region is configured to not buckle in response to the external incident force, wherein a height of the first plurality of filaments substantially spans the space between the inner layer and the outer layer, and wherein a height of the second plurality of filaments does not substantially span the space between the inner layer and the outer layer.

[0005] According to another aspect there is provided a helmet comprising:
an inner layer; an outer layer spaced apart from the inner layer to define a space, wherein the space comprises a material selected from the group consisting of a gas, a liquid, a gel, a foam, a polymeric material, and any combination thereof; and an interface layer disposed in the space between the inner layer and the outer layer, the interface layer comprising a plurality of filaments, each of the plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer and each of the plurality of filaments having an average aspect ratio of between 3:1 and 1,000:1, wherein an external incident force creates a local deformation region of the helmet, wherein at least a first portion of the plurality of filaments within the local deformation region of the helmet is configured to buckle in response to the external incident force, and wherein a second portion of the plurality of filaments immediately adjacent to the local deformation region is configured to not buckle in response to the external incident force.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A is a perspective view of a protective helmet configured in accordance with embodiments of the present technology.

[0007] Figure 1B is a perspective cross-sectional view of the protective helmet shown in Figure 1A.

[0008] Figure 2A¨C illustrate various embodiments of filaments configured for an interface layer of a protective helmet configured in accordance with the present technology.

[0009] Figure 3A¨D illustrate deformation of portion of an interface layer configured in accordance with embodiments of the present technology.

[0010] Figures 4A and 4B illustrate an interface layer including a plurality of segmented tiles in accordance with embodiments of the present technology.

[0011] Figures 5A¨I illustrate ,various filament configurations and shapes in accordance with embodiments of the present technology.

[0012] Figure 6 is a graph of the stress-strain behavior of an interface layer configured in accordance with embodiments of the present technology.

[0013] Figure 7 illustrates a variety of filament densities for the interface layer in accordance with embodiments of the present technology.

[0014] Figure 8 is a cross-sectional view of a protective helmet having an interface layer with a plurality of filaments extending from an outer surface of the helmet in accordance with embodiments of the present technology.

[0015] Figure 9A is a cross-sectional view of a protective helmet having an interface layer with two different types of filaments configured in accordance with embodiments of the present technology.

[0016] Figure 9B is an enlarged detail view of the protective helmet shown in Figure 9A

[0017] Figure 9C is a cross-sectional view of the protective helmet shown in 9A under local deformation.

[0018] Figure 9D is an enlarged detail view of the protective helmet shown under local deformation in Figure 9C.

[0019] Figure 10 is a flow diagram of a method of manufacturing an interface layer in accordance with embodiments of the present technology.

[0020] Figure 11 is a flow diagram of another method of manufacturing an interface layer in accordance with embodiments of the present technology.

[0021] Figure 12 is a perspective cross-sectional view of a protective helmet with filaments incorporating force sensors configured in accordance with embodiments of the present technology.

[0022] Figures 13a to 13e illustrate enlarged views of different configurations of filaments in localized regions.

[0023] Figure 14 illustrates a cross-sectional view of a vented protective helmet and an enlarged view of an embodiment of a vented filament.
- 3a -DETAILED DESCRIPTION

[0024] The present technology is generally related to protective helmets with non-linearly defoiming elements therein. Embodiments of the disclosed helmets, for example, comprise an inner layer, an outer layer, and an interface layer disposed in a space between the inner and outer layers. The interface layer can include a plurality of filaments configured to defoim non-linearly in response to an incident force.

[0025]
Specific details of several embodiments of the present technology are described below with reference to Figures 1A-14. Although many of the embodiments are described below with respect to devices, systems, and methods for protective helmets, other embodiments are within the scope of the present technology. Additionally, other embodiments of the present technology can have different configurations, components, and/or procedures than those described herein. For example, other embodiments can include additional elements and features beyond those described herein, or other embodiments may not include several of the elements and features shown and described herein.

[0026] For ease of reference, throughout this disclosure identical reference numbers are used to identify similar or analogous components or features, but the use of the same reference number does not imply that the parts should be construed to be identical.
Indeed, in many examples described herein, the identically numbered parts are distinct in structure and/or function.
Selected Embodiments of Protective Helmets [0027-30]
Figure 1A is a perspective view of a protective helmet 101 configured in accordance with embodiments of the present technology. Figure 1B is a perspective cross-sectional view of the helmet shown in Figure 1A. Referring to Figures 1A and 1B together, the - 3b -helmet 101 comprises an outer layer 103, an inner layer 105, and space or gap 107 between the outer layer 103 and the inner layer 105. An interface layer 109 comprising a plurality of filaments 111 is disposed in the space 107 between the outer layer 103 and the inner layer 105.
In the illustrated embodiment, the filaments 111 extend between an outer surface 113 adjacent to the outer layer 103 and an inner surface 115 adjacent to the inner layer 105, and span or substantially span the space 107. Padding 117 is disposed adjacent to the inner layer 105. The padding 117 can be configured to comfortably conform to a head of the wearer (not shown).
[0031] In some embodiments, the outer layer 103 of the helmet 101 may be composed of a single, continuous shell. In other embodiments, however, the outer layer 103 may have a different configuration. The outer layer 103 and the inner layer 105 can also both be relatively rigid (e.g., composed of a hard plastic material). The outer layer 103, however, can be pliable enough to locally deform when subject to an incident force. In certain embodiments, the inner layer 105 can be relatively stiff, thereby preventing projectiles or intense impacts from fracturing the skull or creating hematomas. In some embodiments, the inner layer 105 can be at least five times more rigid than the outer layer 103. In some embodiments, the outer layer 103 may also comprise a plurality of deformable beams that are flexibly connected and arranged so that the longitudinal axes of the beams are substantially parallel to the surface of the outer layer.
Further, in some embodiments each of the deformable beams can be flexibly connected to at least one other deformable beam and at least one filament.
[0032] The filaments 111 can comprise thin, columnar or elongated structures configured to deform non-linearly in response to an incident force on the helmet 101.
Such structures can have a high aspect ratio, e.g., from 3:1 to 1000:1, from 4:1 to 1000:1, from 5:1 to 1000:1, from 100:1 to 1000:1, etc. The non-linear deformation of the filaments 111 is expected to provide improved protection against high-impact direct forces, as well as oblique forces. More specifically, the filaments 111 can be configured to buckle in response to an incident force, where buckling may be characterized by a sudden failure of filament(s) 111 subjected to high compressive stress, where the actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding.
The filaments 111 can be configured to deform elastically, so that they substantially return to their initial configuration once the external force is removed.
[0033] At least a portion of the filaments 111 can be configured to have a tensile strength so as to resist separation of the outer layer 103 from the inner layer 105.
For example, during lateral movement of the outer layer 103 relative to the inner layer 105, those filaments 111 having tensile strength may exert a force to counteract the lateral movement of the outer layer 103 relative to the inner layer 105. In some embodiments, there may be wires, rubber bands, or other elements embedded in or otherwise coupled to the filaments 111 in order to impart additional tensile strength.
[0034] As shown in the embodiment illustrated in Figure 1B, for example, the filaments 111 may be directly attached to the outer layer 103 and/or directly attached to the inner layer 105. In some embodiments, at least some of the filaments 111 can be free at one end, with an opposite end coupled to an adjacent surface. Due to the flexibility of the filaments 111, the outer layer 103 can move laterally relative to the inner layer 105. In some embodiments, the filaments 111 can optionally include a rotating member at one or both ends that is configured to rotatably fit within a corresponding socket in the inner or outer layers. In some embodiments, at least some of the filaments 111 can be substantially perpendicular to the inner surface 115, the outer surface 113, or both.
[0035] The filaments 111 may be composed of a variety of suitable materials, such as a foam, elastomeric material, polymeric material, or any combination thereof In some embodiments, the filaments can be made of a shape memory material and/or a self-healing material. Furthermore, in some embodiments, the filaments may exhibit different shear characteristics in different directions.
[0036] In some embodiments, the helmet 101 can be configured to deform locally and elastically in response to an incident force. In particular embodiments, for example, the helmet 101 can be configured such that upon application of between about 100 and 500 static pounds of force, the outer layer 103 and interface layer 109 deform between about 0.75 to 2.25 inches.
The deformability can be tuned by varying the composition, number, and configuration of the filaments 111, and by varying the composition and configuration of the outer layer 103 and inner layer 105.
[0037] Figure 2A¨C illustrate various embodiments of filaments configured for an interface layer (e.g., interface layer 109) of a protective helmet (e.g., helmet 101) in accordance with embodiments of the present technology. Referring to Figure 2A, for example, a plurality of filaments 211a have a cross-sectional shape of regular polygons. Individual filaments 211a have a height 201, a width 203, and a spacing 205 between adjacent filaments 211a.
Referring to Figure 2B, filaments 211b can be connected to an inner surface 215 at one end, and can be free at the opposite end. In Figure 2C, filaments 211c can be coupled to a spine 207 at a middle point of the filaments 211c, such that the filaments 211c extend outwardly in opposite directions from the spine 207. Referring to Figures 2A-2C together, the filaments 211a¨c can assume any suitable shape, including cylinders, hexagons (inverse honeycomb), square, irregular polygons, random, etc. The point of connection between the filaments 211a¨c and the inner surface 215 or the spine 207, the dimensions 201, 203, and 205, the filament material, the material in the space between the filaments 211a¨c, can all be modified to tune the orthotropic properties of the filaments. This tunability is expected to provide desired deformation properties and can be varied between different regions of the interface layer. The filaments 211a¨c can be made from any material that allows for large elastic deformations including, for example, foams, elastic foams, plastics, etc. The spacing between filaments 211a-c can be filled with gas, liquid, or complex fluids, to further tune overall structure material properties. In some embodiments, for example, the space can be filled with a gas, a liquid (e.g., a shear thinning or shear thickening liquid), a gel (e.g., a shear thinning or shear thickening gel), a foam, a polymeric material, or any combination thereof.
[0038] Figure 3A¨D illustrate deformation of an interface layer 309 having an outer surface 313, an inner surface 315, and a plurality of filaments 311 extending between the outer surface 313 and the inner surface 315. Figure 3A, for example, illustrates the interface layer 309 without an external force applied. In Figure 3B, a downward force F1 is applied to the outer surface 313, resulting in deformation of a portion of the filaments 311.
Figure 3C illustrates translation of the outer surface 313 with respect to the inner surface 315 in response to a tangential force F2. In Figure 3D, a vertical and tangential force F3 results in deformation of the filaments 311. Oblique and/or tangential forces that are distributed over a larger area of the outer surface 313 can result in shear of the filaments 311 or local buckling of some of the filaments 311.
[0039] Figures 4A and 4B illustrate an interface layer 409 including a plurality of segmented tiles configured in accordance with embodiments of the present technology. A
plurality of filaments 411 are affixed to and extend away from an inner surface 415. An outer surface 413 of the interface layer 409 is divided into a plurality of segmented tiles 414 (three are shown as tiles 414a¨c). As best seen in Figure 4B, the filaments 411 throughout the interface layer 409 share the common inner surface 415, but only a subset of the filaments 411 are coupled together to define individual segmented tiles 414a¨c. In Figures 4A
and 4B, the tiles 414a¨c are shown as packed hexagons, but in other embodiments the tiles 414a¨c could take other shapes including regular and irregular polygons, cylinders, etc. The tiles 414 are arranged to allow for a set of filaments 411 to respond to local impact forces and buckle, shear, or otherwise move relative to the other neighboring tiles 414. In some embodiments, some tiles 414 can be configured to move on top of or below neighboring tiles 414 in response to impact forces.
In certain embodiments, the tiles 414 may be flexibly connected to one another. The tiles 414a¨e can be configured to tessellate with each other. The space between the tiles 414a¨c can be air, or the space may be filled with a different material (e.g. foam, liquid, gel, etc.).
[0040] Figures 5A-5I illustrate various filament configurations and shapes in accordance with embodiments of the present technology. The filaments of Figures 5A-5I may be used with any of the interface layers disclosed herein. Referring first to Figure 5A, for example, an interface layer 509 comprises a plurality of filaments 511a extending from an inner surface 515a, with an outer surface 513a divided into separate discrete portions.
Figure 5B illustrates the interface layer 509 being flexibly curved. For example, the interface layer 509 may be curved to correspond to the curvature of a helmet. The material of the filaments 511a, the outer surface 113a, and/or the inner surface 115a can be flexible to permit such bending.
[0041] Figures 5C¨F illustrate plan views of an arrangement of filaments 511c¨i in the interface layer 509. The filaments 511c can have a uniform size and shape, and be distributed isotropically (as in Figure 5C). With respect to Figure 5D, some filaments 511d are larger than others, and they can be distributed non-uniformly. In Figures 5E and 5F, the filaments 51Ie assume irregular shapes and patterns. Figures 5G-5I illustrate side views of single filaments 511g¨i having various configurations. In Figure 5G, for example, the filament 511g is connected to the inner surface 515g, but is separated from the outer surface 513g. In Figure 5H, the filament 511h has a varying thickness along its length. In Figure 51, the filament 511h is hollow, for example a hollow cylinder. In certain embodiments, one or more of the filaments can be hollow, such that the filament includes a lumen that extends a portion of the distance along the height of the filament. Such lumens could be configured to facilitate airflow through the space between the inner layer and the outer layer thereby cooling the wearer's head as shown in Figure 14. In other embodiments, the plurality of filaments is configured to provide a region in the space between the inner layer and the outer layer that is relatively free of filaments as shown in helmet cross-sectional view of Figure 14. In certain further embodiments, this region is proximate to one or more vents or apertures disposed on the outer layer or outer layer of the helmet. The arrangement, size, and shape of the filaments can be varied to achieve the desired mechanical properties of the corresponding interface layer, for example deformation properties, stiffness, etc.
[0042] In some embodiments, the filaments can be disposed between the outer surface and the inner surface such that a longitudinal axis of the filament is not perpendicular to either the outer surface or the inner surface. In certain embodiments, the outer surface or outer layer is pliable enough to locally deform or buckle when subject to an incident force.
Furthermore, in certain embodiments, the inner layer is composed of relatively stiff material and a plurality of pads is configured to conform to the head of the wearer. In some embodiments, the angle, shape and configuration of the filaments disposed between the inner layer and outer layer may be different (See Figures 13a ¨ 13e). Figure 13a illustrates filaments that have locally tightened spacing. Alternatively, there can be larger filaments locally as shown in Figure 13b. In other embodiments, the filaments may be asymmetric shaped. Figure 13c illustrates one asymmetric shaped embodiment that has ani otropic mechanical behavior. Furthermore, in other embodiments, the longitudinal axis of each of the plurality of filaments may positioned at an angle as shown in Figure 13d. In some embodiments, the angle of the longitudinal axis of a first subset of filaments relative to at least one of the outer surface and/or inner surface can be supplementary to the angle of the longitudinal axis of a second subset of filaments relative to the outer surface and/or the inner surface as shown in Figure 13e. For example, a first filament can have a longitudinal axis disposed at a 30 degree angle with respect to the inner surface, and a second filament can have a longitudinal axis disposed at a 150 degree angle with respect to the inner surface. In some embodiments, the first and second filaments can be connected to one another at an intersection point as shown in Figure 13e.
[0043] Figure 6 is a graph of stress-strain behavior of the interface layer in accordance with embodiments of the present technology. As illustrated, as the strain (D) increases, the stress (G) initially increases rapidly in region I. Next, in region II, the stress is relatively flat, followed by a further increase of the stress in region III. This nonlinear relationship exhibits behavior similar to those observed in buckling in which there is an initial stiff region (region I), followed by a rapid transition to a flat, decreasing, or increasing slope (region II), followed by a third region with a different slope (region III). As depicted in Figure 6, the dashed lines illustrate possible alternative stress-strain profiles for an interface layer. As the materials, arrangement and configuration of filaments within the interface layer are varied, the stress-strain relationship can be adjusted to achieve a desired profile. In some embodiments, the interface layer can be orthotropic (i.e., exhibiting different nonlinear stress-strain behaviors for different components of stress). The stress-strain behavior is in contrast to a linearly deforming helmet, in which the acceleration impart to the head is much higher. As depicted in Figure 6, a linearly deforming helmet is predicted to impart a much higher acceleration than a non-linearly deforming helmet, such as the helmets described herein. This is the case for both direct and oblique forces incident on linearly and non-linearly deforming helmets.
[0044]
Figure 7 illustrates a variety of filament densities for a protective helmet in accordance with embodiments of the present technology. As noted above, a protective helmet can include an interface layer comprising a plurality of filaments therein.
The deformation characteristics of the interface layer can be adjusted/tuned based on a composition and arrangement of the filaments. As illustrated in Figure 7, the arrangement and density of filaments can vary at different locations of the helmet. For example, the density of filaments may be greatest in the front and back portions, with a lower density of filaments on left and right, and an even lower density of filaments over the left and right ears.
Because a wearer of the help may be at greater risk of receiving a high-impact force from the front or back, those portions of the helmet can have a greater density of filaments that the portion of the helmet than over the wearer's ear. The density and configuration of filaments can accordingly be varied across the helmet to account for the types and frequencies of impact expected.
- 8a -[0045] Figure 8 is a cross-sectional view of a protective helmet 801 having a plurality of filaments 811 extending from the outer layer 803. As illustrated, the filaments 811 are not attached to an inner layer. Padding 817 is disposed inward from the filaments 811. This configuration can allow for tunable shear characteristics, as well as tunable non-linear deformation of the filaments 811.
[0046] Figure 9A is a cross-sectional view of a protective helmet 901 having an interface layer 909 with two different types of filaments 911 and 912 configured in accordance with embodiments of the present technology. Figure 9B is an enlarged detail view of a portion of the helmet 901. Referring to Figures 9A and 9B together, the helmet 901 comprises an outer layer 903, an inner layer 905, and an interface layer 909 disposed between the outer layer 903 and the inner layer 905. The interface layer 909 comprises a first plurality of filaments 911 that span or substantially span the space between the inner layer 905 and the outer layer 903. The interface layer 909 also comprises a second plurality of filaments 912 that do not substantially span the space. Padding 917 is disposed adjacent to inner layer 905. The inclusion of two different types of filaments, each having different shapes, lengths, and/or stiffnesses, is expected to provide increased control of the overall material characteristics of the interface layer 909. For example, in some embodiments the second filaments 912 can be shorter and stiffer than the first filaments 911. Upon initial deformation of the outer layer 103, the first filaments 911 can provide some resistance. Once the outer layer 903 has compressed enough that the second plurality of filaments 912 come into contact with the more rigid inner layer 905, the second plurality of filaments 912 can contribute to a greater resistance of the interface layer 909 to the impact force.
Figures 9C and 9D, for example, illustrate the protective helmet 901 under local deformation.
The first and second filaments 911 and 912 both deform non-linearly in response to the impact force incident on the outer layer 903 of the helmet 901. The deformation can be elastic, such that after impact the interface layer 909 and outer layer 903 return to their original configurations. In some embodiments, the helmet 901 can be configured such that upon application of between about 100 and 500 static pounds of force, the outer layer 903 and interface layer 909 deform between about 0.75 to 2.25 inches. The deformability can be tuned by varying the composition, number, and configuration of the filaments 911, and by varying the composition and configuration of the outer layer 903 and inner layer 905.

Selected Embodiments of Methods for Manufacturing Interface Layers for Protective Helmets [0047] Figure 10 is a flow diagram of a method of manufacturing an interface layer in accordance with embodiments of the present technology. The process 1000 begins in block 1001 by providing a first surface. The first surface can be, for example, a sheet of a polymer, plastic, foam, elastomer, or other material suitable for forming filaments. Process 1000 continues in block 1003 by providing a second surface. In some embodiments, the second surface can have similar characteristics to the first surface. In block 1005, an interstitial member is provided between the first surface and the second surface. The interstitial member can be, for example a plate having a plurality of apertures therein. The apertures can define the cross-sectional shapes and the distribution of the ultimate filaments to be formed between the first and second surfaces.
For example, in some embodiments one or more of the apertures can assume the shape of a square, a rectangle, a triangle, an ellipse, a regular polygon, or other shape. In block 1007, the first and second surfaces are compressed against the interstitial member so that a portion of the first and/or sccond surface protrudes into an aperture of the interstitial member. In block 1009, the first and second surfaces are heated above their glass transition temperatures, resulting in a merging of the first and second surfaces and the portions of the first and/or second surface which extend through the apertures of the interstitial member to the other surface.
These portions extending through the apertures become the filaments of the interface layer.
The process concludes in block 1011 with removing the interstitial member. In some embodiments, removing the interstitial member can comprise burning the interstitial member, dissolving the interstitial member, or otherwise removing it. In some embodiments, after removing the interstitial member the space between the first surface and the second surface can be filled with a gas, a liquid, or a gel.
[0048] Figure 11 is a flow diagram of another method of manufacturing an interface layer in accordance with embodiments of the present technology. The process 1100 begins in block 1101 by providing a first surface having a plurality of first protruding members. For example, the first surface can be a sheet having a plurality of raised portions, such as columns or bumps.
Process 1100 continues in block 1103 by providing a second surface having a plurality of second protruding members that face the first protruding members of the first surface. In block 1105, at least one of the first protruding members is aligned with at least one of the second protruding members. In block 1107, the first and second surfaces are heated above their glass transition temperatures. The process 1100 continues in block 1109 by bringing the at least one first - io -protruding member into contact with the at least one second protruding members. As the materials have been heated above their glass transition temperatures, the first protruding member and the second protruding member are joined by this contact. In block 1111, the first surface is withdrawn from the second surface. This can extend the length of the joined first and second protruding members, resulting in a filament extending between the first surface and the second surface. In some embodiments, the first and second protruding members can comprise a foam, a a polymer, an elastomer, or other suitable material. In some embodiments, the cross-sectional shape of the protruding members can be square, rectangular, triangular, elliptical, a regular polygon, or other shape. In some embodiments, the space between the first surface and the second surface can be filled with a gas, a liquid, or a gel.
Selected Embodiments of Protective Helmets Incorporating Force Sensors [0049] In some embodiments, the filaments in the interface layer of the helmet can also serve as force sensors or substrates for mounting force sensors. Figure 12 is a perspective cross-sectional view of a protective helmet with filaments incorporating force sensors. The helmet 1201 comprises an outer layer 1203, an inner layer 1205, and an interface layer 1209 disposed between the outer layer 1203 and the inner layer 1205. The interface layer 1209 comprises a plurality of filaments 1211 that span or substantially span the space between the inner layer 1205 and the outer layer 1203. Force sensors 1212 (shown schematically) are coupled to the filaments 1211. In some embodiments, a wire or film could be embedded in, or on, each filament 1211. In some embodiments, the sensors1212 can be sized and configured to produce a signal indicative of strain or deformation along the longitudinal axes of the filaments. These sensors 1212 can be configured to detect strain and or deformation of individual filaments 1211.
The strain or deformation of the filament 1211 and sensor may then be related back to force using the known mechanical properties of the filaments 1211 and helmet 1201 structure. In some embodiments, the filament may be used directly as the sensor by providing the filament with electrical properties. For example, the filaments 1211 may have doped particles embedded to provide conductivity or piezoresistive properties. Deformation will then result in a change in electrical properties (e.g., resistance), allowing for electrical measurement of force. In some embodiments, the filaments 1211 can be made piezoelectric, allowing the filaments to generate electrical potential or current when deformed. In some embodiments, a sensor can comprise an optical waveguide with a first end and a second end, a light source incident upon one end of the optical waveguide, and a photodetector adjacent to the opposite end of the optical waveguide configured to receive light transmitted through the optical waveguide. In some embodiments, the waveguide can be a Bragg diffraction grating. In some embodiments, the Bragg diffraction gratings in each of the plurality of sensors can have unique periodicities.
[0050] The plurality of sensors can be logically coupled to a computing device and/or a data storage device capable of storing strain and deformation signals received from the plurality of sensors. In some embodiments, a wireless communication device can be coupled to the data storage device and configured to wirelessly transmit data stored on the data storage device to a second computing device. For example, in some embodiments the data storage device and wireless communication device can be embedded within the helmet, and can transmit the stored data to an external computing device. In some embodiments, the data storage device can include stored therein computer-readable prop-am instructions that, upon execution by the computing device, cause the computing device to determine the magnitude and direction of a force incident upon the helmet based on the strain or deformation signals generated from the plurality of sensors. In some embodiments, the computing device can be configured to determine the acceleration of the wearer's head caused by the incident force. In some embodiments, the computing device can provide a signal indicating when the helmet has received incident forces over a defined threshold.
[0051] By embedding sensors in individual filaments, a plurality of sensors can be integrated into the helmet structure and provide single filament resolution of force transmission.
Data from the sensors can be used to quantify hit number, magnitude, and location, to correlate hit magnitude with location and acceleration, to determine the likelihood of traumatic brain injury. The data may also be used to evaluate the current condition of the helmet and possible need for refurbishment or replacement. The data from individual players can be used to tune the material characteristics of the helmet for an individual's style of play and or position. For example in football, centers may tend to receive hits top center while wide receivers may tend to receive hits tangentially on the rear comer. This impact fitting process is unique from the helmet functionality and comfort fitting.
Examples 1. A helmet, comprising:
an inner layer;
an outer layer spaced apart from the inner layer to define a space;

an interface layer disposed in the space between the inner layer and the outer layer, wherein the interface layer comprises a plurality of filaments, the individual filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer, wherein the filaments are configured to deform non-linearly in response to an external incident force on the helmet.
2. The helmet of example 1 wherein the outer layer moves laterally relative to the inner layer in response to an external oblique force on the helmet.
3. The helmet of any one example 1 or example 2 wherein the filaments are configured to buckle in response to axial compression.
4. The helmet of any one of examples 1-3 wherein the individual filaments have an aspect ratio of between 3:1 and 1,000:1.
5. The helmet of any one of examples 1-4 wherein the filaments comprise a material selected from the group consisting of: a foam, an elastomer, a polymer, and any combination thereof 6. The helmet of any one of examples 1-4 wherein the filaments are composed of a shape memory material.
7. The helmet of any one of examples 1-6 wherein the filaments comprise a self-healing material.
8. The helmet of any one of examples 1-7 wherein the filaments exhibit different shear characteristics in different directions.
9. The helmet of any one of examples 1-8 wherein at least a portion of the filaments have a non-circular cross-sectional shape.

10. The helmet of any one of examples 1-8 wherein the filaments have a cross-sectional shape selected from one of the following: circular, hexagonal, triangular, square, and rectangular.
11. The helmet of any one of examples 1-10 wherein a density of the filaments is higher in some portions of the interface layer than in other portions of the interface layer.
12. The helmet of any one of examples 1-11 wherein a thickness of each filaments varies along a length of the filament.
13. The helmet of any one of examples 1-12 wherein the inner layer and/or outer layer further comprise a plurality of sockets, and wherein:
the filaments further comprise a rotating member attached to at least one of the first end and the second end, the rotating member being configured to rotatably fit within one of the plurality of sockets.
14. The helmet of any one of examples 1-13 wherein at least a portion of the filaments are attached to the inner layer.
15. The helmet of any one of examples 1-14 wherein at least a portion of the filaments are attached to the outer layer.
16. The helmet of any one of examples 1-15 wherein each filament extends along a longitudinal axis, and wherein the longitudinal axes of the filaments are substantially perpendicular to a surface of at least one of the inner layer and the outer layer.
17. The helmet of any one of examples 1-16 wherein the outer layer comprises a plurality of segments, wherein at least one of the segments is configured to move relative to the other segments upon receiving an external incident force.
18. The helmet of example 17 wherein the second ends of the filaments are attached to one of the plurality of segments.

19. The helmet of example 17, further comprising resilient spacing members which flexibly couples the plurality of segments to one another.
20. The helmet of any one of examples 1-19 wherein the outer layer comprises an elastically deformable material.
21. The helmet of any one of examples 1-20 wherein the outer layer comprises a plurality of deformable beams, each having two ends and a longitudinal axis, wherein the ends of each of the plurality of deformable beams are flexibly connected to at least one other deformable beam, and wherein the longitudinal axis is parallel to the surface of the outer layer.
22. The helmet of example 21 wherein the ends of each of the deformable beams are flexibly connected to at least one other deformable beam and at least one of the filaments.
23. The helmet of any one of examples 1-22 wherein the inner layer comprises a shell configured to substantially surround the head of a wearer.
24. The helmet of any one of examples 1-23 wherein the inner layer comprises a material having a rigidity at least five times more rigid than the outer layer.
25. The helmet of any one of examples 1-24 wherein the inner layer comprises padding configured to substantially conform to the contours of a head.
26. The helmet of any one of examples 1-25 wherein at least one of the filaments is hollow.

27. The helmet of any one of examples 1-26 wherein at least one of the filaments is conical.

28. The helmet of any one of examples 1-27 wherein a longitudinal axis of a first filament of the plurality of filaments is not perpendicular to either the inner layer or the outer layer.

29. The helmet of example 28 wherein a longitudinal axis of a second filament of the plurality of filaments is not parallel to the longitudinal axis of the first filament.

30. The helmet of example 29 wherein an angle of the longitudinal axis of the first filament relative to at least one of the inner layer and the outer layer is supplementary to an angle of the longitudinal axis of the second filament relative to at least one of the inner layer and the outer layer.

31. The helmet of example 30 wherein the first filament is connected to the second filament at an intersection point.

32. A helmet comprising:
an inner layer;
an outer layer spaced apart from the inner layer to define a space; and an interface layer disposed in the space between the inner layer and the outer layer, wherein the interface layer comprises:
a first plurality of filaments, the individual first filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer;
and a second plurality of filaments, the second individual filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer;
wherein the first and second filaments are configured to deform non-linearly in response to an incident force, wherein a height of the first filaments substantially spans the space between the inner layer and the outer layer, and wherein a height of the second filaments does not substantially span the space between the inner layer and the outer layer.

33. The helmet of example 32 wherein the first ends of the second filaments are attached to the inner layer.

34. The helmet of example 32 or example 33 wherein the second ends of the second filaments are attached to the outer layer.

35. The helmet of any one of examples 32-34 wherein the second filaments have a lower aspect ratio than the first filaments.

36. The helmet of any one of examples 32-35 wherein the second filaments are more rigid than the first filaments.

37. A helmet comprising:
an inner layer;
an outer layer spaced apart from the inner layer to define a space, wherein the space comprises a material selected from the group consisting of a gas, a liquid, a gel, a foam, a polymeric material, and any combination thereof; and an interface layer disposed in the space between the inner layer and the outer layer, the interface layer comprising a plurality of filaments, each individual filament comprising a first end proximal to the inner layer and a second end proximal to the outer layer, wherein the filaments are configured to deform non-linearly in response to an incident external force.

38. The helmet of example 37 wherein the liquid comprises a shear thinning liquid.

39. The helmet of example 37 wherein the liquid comprises a shear thickening liquid.

40. The helmet of example 37 wherein the liquid comprises a shear thinning gel.

41. The helmet of example 37 wherein the liquid comprises a shear thickening gel.

42. A method of making an interface layer comprising at least one filament disposed between a first surface and a second surface, the method comprising:
providing a first surface comprising a plurality of first protruding elements protruding from the first surface;

providing a second surface comprising a plurality of second protruding elements protruding from the second surface, the second surface disposed opposite the first surface such at least one of the first protruding elements is aligned with at least one of the second protruding elements;
heating the first surface and second surface above their glass transition temperatures;
bringing the at least one first protruding element in contact with the at least one second protruding element; and withdrawing the first surface from the second surface, thereby providing at least one filament disposed between the first surface and the second surface.

43. The method of example 42 wherein the first protruding elements and second protruding elements comprise a foam.

44. The method of example 42 wherein the plurality of first protruding elements and the plurality of second protruding elements comprise a polymer.

45. The method of any one of examples 42-44 wherein the first protruding elements and the second protruding elements comprise a cross-sectional shape selected from the group consisting of: a square, a rectangle, a triangle, and an ellipse.

46. The method of any one of examples 42-45 wherein the first protruding elements and the second protruding elements comprise a cross-sectional shape of a regular polygon.

47. The method of any one of examples 42-46, further comprising filling a space between the first surface and the second surface with a gas, a liquid, or a gel.

48. A method of making an interface layer comprising at least one filament disposed between a first surface and a second surface, the method comprising:
providing a first surface;
providing a second opposite the first surface;
providing an interstitial member, disposed between the first surface and the second surface, comprising a plurality of apertures;

compressing the first surface and the second surface against the interstitial member so that a portion of the first surface and/or a portion of the second surface protrudes into the plurality of apertures;
heating the first surface and the second surface above their glass transition temperatures;
and removing the interstitial member, thereby providing at least one filament disposed between the first surface and the second surface.

49. The method of example 48 further comprising withdrawing the first surface from the second surface.

50. The method of example 48 or example 49 wherein removing the interstitial member comprises burning the interface layer.

51. The method of example 48 or example 49 wherein removing the interstitial member comprises dissolving the interface layer.

52. The method of any one of examples 48-51 wherein the filament comprises a foam.

53. The method of any one of examples 48-52 wherein the filament comprises a polymer.

54. The method of any one of examples 48-53 wherein the apertures in the interstitial member are configured in a shape selected from the group consisting of: a square, a rectangle, a triangle, and an ellipse.

55. The method of any one of examples 48-54 wherein the apertures in the interstitial member are configured in the shape of a regular polygon

56. The method of any one of examples 48-55, further comprising filling the space between the first surface and the second surface with a gas, a liquid, or a gel.

57. A helmet comprising:
an inner layer;
an outer layer configured to provide a space between the inner layer and the outer layer;
an interface layer disposed in the space between the inner layer and the outer layer, the interface layer comprising a plurality of filaments, each individual filament comprising a first end proximal to the inner layer and a second end proximal to the outer layer; and a plurality of sensors coupled to at least a subset of the filaments, wherein the filaments arc configured to deform non-linearly in response to an external incident force.

58. The helmet of example 57 wherein the sensors are sized and configured to produce a signal indicative of strain or deformation of the filaments.

59. The helmet of any one of examples 57-58 wherein the sensors comprise a wire or film.

60. The helmet of any one of examples 57-58 wherein the sensors comprise conductive polymer filaments.

61. The helmet of any one of examples 57-58 wherein the sensors comprise a plurality of doped particles.

62. The helmet of any one of examples 57-58 wherein the sensors comprise piezoelectric sensors.

63. The helmet of any one of examples 57-58 wherein the sensors comprise an optical waveguide with a first end and a second end, a light source incident upon one end of the optical waveguide, and a photodetector adjacent to the opposite end of the optical waveguide configured to receive light transmitted through the optical waveguide.

64. The helmet of example 63 wherein the optical waveguide comprises a Bragg diffraction grating.

65. The helmet of example 64 wherein the Bragg diffraction gratings in each of the sensors has a unique periodicity.

66. The helmet of any one of examples 57-65, further comprising:
a computing device logically coupled to the sensors; and a data storage device, capable of storing strain and deformation signals from the plurality of sensors.

67. The helmet of example 66, further comprising a wireless communication device configured to wirelessly transmit data stored on the data storage device to a second computing device.

68. The helmet of example 66, the data storage device having stored therein computer-readable program instructions that, upon execution by the computing device, cause the computing device to perform functions comprising:
determining a magnitude and a direction of a force incident upon the helmet based upon the strain or deformation signals generated from the sensors.

69. The helmet of example 68 wherein the functions further comprise determining an acceleration of a head of a wearer caused by the incident force.

70. The helmet of example 66, further comprising an indicator that provides a signal indicating when the helmet has received incident forces over a defined threshold.
Conclusion [0052] The above detailed descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise form disclosed above. Although specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein may also be combined to provide further embodiments. Various modifications can be made without deviating from the spirit and scope of the disclosure. For example, the interface layer can include filaments having any combination of the features described above. Additionally, the features of any particular embodiment described above can be combined with the features of any of the other embodiments disclosed herein.
[0053] From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but well-known structures and functions have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments of the technology. Where the context permits, singular or plural terms may also include the plural or singular term, respectively.
[0054] Moreover, unless the word "or" is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of "or" in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. Additionally, the term "comprising" is used throughout to mean including at least the recited feature(s) such that any greater number of the same feature and/or additional types of other features are not precluded.
It will also be appreciated that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. Further, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Claims

What is claimed is:

1. A helmet comprising:
an inner layer;
an outer layer spaced apart from the inner layer to define a space; and an interface layer disposed in the space between the inner layer and the outer layer, the interface layer comprising a first plurality of filaments and a second plurality of filaments, each of the first and second plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer, each of the first and second plurality of filaments having a longitudinal axis and having an average aspect ratio of between 3:1 and 1,000:1, wherein an external incident force creates a local deformation region of the helmet, wherein the first plurality of filaments within the local deformation region is configured to buckle in response to the external incident force, and wherein the second plurality of filaments immediately adjacent to the local deformation region does not buckle in response to the external incident force on the helmet.

2. The helmet of claim 1, wherein the outer layer moves laterally relative to the inner layer in response to an external oblique force on the helmet.

3. The helmet of claim 1 or 2, wherein the buckling comprises a localized lateral deflection of a central region of each of the first plurality of filaments.

4. The helmet of any one of claims 1 to 3, wherein a majority of the plurality of filaments have an aspect ratio of between 3:1 and 1,000:1.

5. The helmet of any one of claims 1 to 4, wherein the plurality of filaments comprise a material selected from the group consisting of: a foam, an elastomer, a polymer, and any combination thereof.

6. The helmet of any one of claims I to 4, wherein the plurality of filaments are composed of a shape memory material.

7. The helmet of any one of claims 1 to 4, wherein the plurality of filaments comprise a self-healing material.

8. The helmet of any one of claims 1 to 7, wherein the plurality of filaments exhibit different shear characteristics in different directions.

9. The helmet of any one of claims 1 to 8, wherein at least a portion of the plurality of filaments have a non-circular cross-sectional shape.

10. The helmet of any one of claims 1 to 8, wherein the plurality of filaments have a cross-sectional shape selected from one of the following: circular, hexagonal, triangular, square, rectangular, and any combination thereof.

11. The helmet of any one of claims 1 to 10, wherein a density of the plurality of filaments is higher in some portions of the interface layer than in other portions of the interface layer.

12. The helmet of any one of claims 1 to 11, wherein a thickness of each of the plurality of filaments varies along a length of the plurality of filaments.

13. The helmet of any one of claims 1 to 12, wherein the inner layer and/or outer layer further comprise a plurality of sockets, and wherein each of the plurality of filaments further comprise a rotating member attached to at least one of the first end and the second end, the rotating member being configured to rotatably fit within one of the plurality of sockets.

14. The helmet of any one of claims 1 to 13, wherein at least a portion of the plurality of filaments are attached to the inner layer.

15. The helmet of any one of claims 1 to 13, wherein at least a portion of the plurality of filaments are attached to the outer layer.

16. The helmet of any one of claims 1 to 15, wherein the longitudinal axes of each of the plurality of filaments are substantially perpendicular to a surface of at least one of the inner layer and the outer layer.

17. The helmet of any one of claims 1 to 16, wherein the outer layer comprises a plurality of segments, and wherein at least one of the plurality of segments is configured to move relative to the other segments upon receiving the external incident force.

18. The helmet of claim 17, wherein the second ends of the plurality of filaments are attached to one of the plurality of segments.

19. The helmet of claim 17 or 18, wherein the plurality of segments is configured to move relative to the other segments, and wherein the helmet further comprises a resilient spacing member which flexibly couples the plurality of segments to one another.

20. The helmet of any one of claims 1 to 19, wherein the outer layer comprises an elastically deformable material.

21. The helmet of any one of claims 1 to 12, wherein the outer layer comprises a plurality of deformable beams, each of the plurality of deformable beams having two ends and a longitudinal axis, and wherein the ends of each of the plurality of deformable beams are flexibly connected to at least one other deformable beam, and the longitudinal axis is parallel to the surface of the outer layer.

22. The helmet of claim 21, wherein the ends of each of the plurality of deformable beams are flexibly connected to at least one other deformable beam and at least one of the plurality of filaments.

23. The helmet of any one of claims 1 to 22, wherein the inner layer comprises a shell configured to substantially surround the head of a wearer.

24. The helmet of any one of claims 1 to 23, wherein the inner layer comprises a material having a rigidity at least five times more rigid than the outer layer.

25. The helmet of any one of claims 1 to 22, wherein the inner layer comprises padding configured to substantially conform to the contours of a head.

26. The helmet of any one of claims 1 to 25, wherein at least one of the plurality of filaments is hollow.

27. The helmet of any one of claims 1 to 25, wherein at least one of the plurality of filaments is conical.

28. The helmet of any one of claims 1 to 12, wherein the longitudinal axis of a first filament of the plurality of filaments is not perpendicular to either the inner layer or the outer layer.

29. The helmet of claim 28, wherein the longitudinal axis of a second filament of the plurality of filaments is not parallel to the longitudinal axis of the first filament.

30. The helmet of claim 29, wherein an angle of the longitudinal axis of the first filament relative to at least one of the inner layer and the outer layer is supplementary to an angle of the longitudinal axis of the second filament relative to at least one of the inner layer and the outer layer.

31. The helmet of claim 30, wherein the first filament is connected to the second filament at an intersection point.

32. A helmet comprising:
an inner layer;
an outer layer spaced apart from the inner layer to define a space; and an interface layer disposed in the space between the inner layer and the outer layer, wherein the interface layer comprises:
a first plurality of filaments, each of the first plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer;
a second plurality of filaments, each of the second plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer;
and each of the first and second plurality of filaments having a longitudinal axis and having an average filament aspect ratio of between 3:1 and 1,000:1, wherein an external incident force creates a local deformation region of the helmet, at least a first portion of the first plurality of filaments within the local deformation region is configured to buckle in response to the external incident force and a second portion of the first plurality of filaments immediately adjacent to the local deformation region is configured to not buckle in response to the external incident force, wherein a height of the first plurality of filaments substantially spans the space between the inner layer and the outer layer, and wherein a height of the second plurality of filaments does not substantially span the space between the inner layer and the outer layer.

33. The helmet of claim 32, wherein the first ends of the second plurality of filaments are attached to the inner layer.

34. The helmet of claim 32 or 33, wherein the second ends of the second plurality of filaments are attached to the outer layer.

35. The helmet of any one of claims 32 to 34, wherein the second plurality of filaments has a lower aspect ratio than the first plurality of filaments.

36. The helmet of any one of claims 32 to 35, wherein the second plurality of filaments is more rigid than the first plurality of filaments.

37. The helmet of any one of claims 32 to 36, wherein the buckling is a localized lateral deflection along a portion of the longitudinal axis of the at least a portion of the first and second plurality of filaments.

38. A helmet comprising:
an inner layer;
an outer layer spaced apart from the inner layer to define a space, wherein the space comprises a material selected from the group consisting of a gas, a liquid, a gel, a foam, a polymeric material, and any combination thereof; and an interface layer disposed in the space between the inner layer and the outer layer, the interface layer comprising a plurality of filaments, each of the plurality of filaments comprising a first end proximal to the inner layer and a second end proximal to the outer layer and each of the plurality of filaments having an average aspect ratio of between 3:1 and 1,000:1, wherein an external incident force creates a local deformation region of the helmet, wherein at least a first portion of the plurality of filaments within the local deformation region of the helmet is configured to buckle in response to the external incident force, and wherein a second portion of the plurality of filaments immediately adjacent to the local deformation region is configured to not buckle in response to the external incident force.

39. The helmet of claim 38, wherein the liquid comprises a shear thinning liquid or a shear thickening liquid.

40. The helmet of claim 38 or 39, wherein the first portion of the plurality of filaments configured to buckle is located proximate to an intermediate region of the plurality of filaments.

41. The helmet of any one of claims 38 to 40, wherein the gel comprises a shear thinning gel or a shear thickening liquid.